This invention relates to bilayer safety glazings and more particularly to a method of forming a prelaminate for use in forming a bilayer safety panel.
Laminated glazings for vehicle windshields, sidelights, rear lights, sun-roofs, architectural glass including sky lights, security glass and the like are known. A bilayer form is a laminate of transparent glass and layers of laminated plastic on one side only of the glass. Non-planar bilayer glazing panels are also known as are problems of objectionable streaks, lines, wrinkles and other optical deficiencies in one or more of the plastic layers. Such problems are addressed in the following prior art patents. While moderately successful, the systems of these patents are not without deficiencies.
U.S. Pat. No. 4,944,822--glass and plastic layers are joined by a room temperature bondable adhesive. The separately applied adhesive must be optically compatible with the other components of the bilayer.
U.S. Pat. No. 5,069,734--a shaped plastic prelaminate preformed in the absence of glass is later mated with and bonded to glass of matching curvature. The surface curvature of the bent glass must exactly match the shaped prelaminate or optical properties of the finished bilayer are adversely affected.
U.S. Pat. No. 5,082,515--plastic layers are shaped against and then bonded to glass within an autoclave laminating assembly. Conventional autoclave bonding systems must be revised and cycles extended to accommodate plastic shaping.